According to an military news release, a Sea-Based X-Band (SBX) radar in the middle of the Pacific Ocean was supposed track a target missile launched from Kwajalein Atoll, relaying the data to a ground-based interceptor launched from Vandenberg Air Force Base, Calif. While both the target missile and interceptor launched successfully, the interceptor failed to hit the target. According to the agency, the SBX "did not perform as expected."

It was supposed to be a test of a new concept: using the SBX as the primary engagement radar for the Ground-based Midcourse Defense system. But it was was also supposed to be an advertisement for a missile defense system that was gradually working out the kinks.

President Barack Obama is pursuing a new vision of ballistic missile defense, one billed as a more prudent – and more realistic – alternative to the plans backed by his predecessor. But as the newly released Pentagon review acknowledges, building a capable, and affordable, missile shield won't happen overnight.

As part of the February 1st budget-'n-strategy extravaganza, the Pentagon released the Ballistic Missile Defense Review. It's a blueprint for building missile defenses that are "cost-effective and proven," and that can stand up to realistic testing. The new mantra here is the "phased adaptive approach," which means gradually bulking up regional defenses against short- and medium-range missiles, instead of a more immediate focus on knocking down long-range missiles.

The review is built around this assumption: "Rogue states" like Iran and North Korea don't yet pose a credible threat to U.S. territory. But the military needs to prepare for a possible surprise advance in the missile threat.

Obama took the first step in this direction when he scrapped plans to site ground-based interceptors in Europe. The new "phased plan" calls for fielding a more advanced sea-based missile interceptor (the Standard Missile-3, pictured here) and stationing more sensors in Europe. The next stage would involve placing land-based SM-3s in southern Europe to expand coverage to more NATO allies; further down the road – 2018 and beyond – the plan calls for improved coverage against medium- and intermediate-range threats by stationing land-based SM-3s somewhere in northern Europe, as well as by fielding an upgraded interceptor, the the SM-3 Block IIA.

The plan also hinges on getting more countries to sign onto this new approach. As we first reported, the U.S. military now has two SM-3 equipped Aegis ballistic missile defense ships on station in the Persian Gulf to respond to the Iranian missile threat; it also has eight Patriot missile batteries in four countries around the region.

International buy-in is also key in Asia, and the new review points to Japan as a model of partnership. Japan has invested heavily in missile-defense assets, buying anti-missile Aegis ships, Patriot Advanced Capability 3 fire units, some early warning radars, and a new command and control system.

This weekend's test, however, was a setback for missile defense. MDA spokesman Rick Lehner told Danger Room the agency would conduct an investigation to determine the cause of the failure to intercept.